Fluid pressure operated fastener driving device

ABSTRACT

A fastener driving device having a fluid pressure operated system for moving a fastener driving element through repeated cycles each of which includes a drive stroke during which a fastener is driven and a return stroke, the main control valve for effecting the cycle of operation being moved by pilot pressure within a pilot chamber acting on a pilot piston forming part of the main control valve, the pilot chamber being communicated with reservoir pressure through a restricted orifice and the exhaust of the pilot chamber being under the control of an auto-fire valve operable to prevent exhaust of the pilot pressure in response to the establishment of a pressure signal in the return plenum chamber at the end of the drive stroke and operable to permit exhaust of the pilot pressure in response to a low pressure signal from the return plenum chamber toward the end of the return stroke. The device also includes an interlock lever pivoted intermediate its ends to the depending stem of the actuating valve and having its ends connected respectively to the trigger member and a motion transmitting member, which, in turn, is connected through a spring to the work contacting member so as to prevent undesired movement of the actuating valve into its closed position as a result of recoil movement of the device when the fastener driving element completes its drive stroke.

United States Patent 72] Inventors Peter A. Readyhough Harrington; Walter G. Lemos, Riverside, R.I. [21] Appl. No. 843,665 [22] Filed July 22, 1969 [45] Patented Mar. 30, 1971 I [73] Assignee Textron Inc.,

Providence, R.I.

[54] FLUID PRESSURE OPERATED FASTENER DRIVING DEVICE 16 Claims, 7 Drawing Figs.

[52] U.S. Cl. 227/8, 227/130 [5 1] Int. Cl. B27f 7/06 [50] Field of Search 227/7, 8, 130

[56] References Cited UNITED STATES PATENTS 3,278,104 10/1966 Becht et a] 227/130 3,278,106 10/1966 Becht et al.... 227/130 3,477,629 11/1969 Becht 227/130 Primary Examiner-Granville Y. Custer, .lr. Att0rney-Cushman, Darby & Cushman ABSTRACT: A fastener driving device having a fluid pressure operated system for moving a fastener driving element through repeated cycles each of which includes a drive stroke during which a fastener is driven and a return stroke, the main control valve for effecting the cycle of operation being moved by pilot pressure within a pilot chamber acting on a pilot piston forming part of the main control valve, the pilot chamber being communicated with reservoir pressure through a restricted orifice and the exhaust of the pilot chamber being under the control of an auto-fire valve operable to prevent exhaust of the pilot pressure in response to the establishment of a pressure signal in the return plenum chamber at the end of the drive stroke and operable to permit exhaust of the pilot pressure in response to a low pressure signal from the return plenum chamber toward the end of the return stroke. The device also includes an interlock lever pivoted intermediate its ends to the depending stem of the actuating valve and having its ends connected respectively to the trigger member and a motion transmitting member, which, in turn, is connected through a spring to the work contacting member so as to prevent undesired movement of the actuating valve into its closed position as a result of recoil movement of the device when the fastener driving element completes its drive strokev Patented March 30, 1971 3,572,572

4 Sheets-Sheet s INVENTORS PE 7277/? Hagar/mac W/M 72-7? G ZA /v05 FMJW PRESSUEE OPERATED FASTENER DRIVING DEVICE This invention relates to fastener driving devices and more particularly to fastener driving devices of the type which are operated by air under pressure.

Fluid pressure operated fastener driving devices are well known in the art. The simplest form of a device of this type is provided with a trigger which, when depressed by the finger of the operator, actuates the fluid pressure system to move the fastener driving element through its drive stroke during which a fastener fed from the fastener magazine is engaged and moved outwardly into the workpiece. When the trigger is released by the operator, the fluid pressure system is operated to move the fastener driving element through its return stroke.

A disadvantage of a simple trigger actuation is that the device is capable of being fired when out of operative relationship with the workpiece, thus presenting the possibility of a fastener becoming a projectile which can cause injury to personnel and the like. In order to overcome this disadvantage, it

has been proposed to provide a work contacting member or contact trip which is interlocked with the trigger such that it is necessary for the operator to both depress the trigger with his finger and to move the entire device into engagement with the workpiece before actuation can occur.

Various interlocking arrangements have been provided which afford the operator essentially'three different types or modes of actuation: first, single firing in which-the operator simple moves the device into contact with the work and depresses the trigger and after the drive stroke has been completed, lifts the device away from the workpiece and releases the trigger; second, bump firing in which the operator continuously depresses the trigger and by successively moving the device into and out of engagement with the workpiece'at specified locations effects firing solely by the movement of the work contacting member; and third, drag firing in which the operator moves the device into contact with the work to actuate the work contacting-member and then moves the device along the work in continuous contact therewith while successively depressing and releasing the trigger to fire the device at spaced locations along the work.

In recent years it has been found'that in certain applications where repeated firing is desired, the time required to operate pneumatic fastener driving devices even when bump or drag fired can be reduced by-modifyingthe pneumatic system so that it will automatically recycle, so long as the trigger is depressed and the work contacting member (when provided) is in engagement with the workpiece. This mode of operation has been called auto-fire."

In some instances it is desirable to provide the fastener driving element with a length sufficient to extend outwardly beyond the work contacting surface of the nose piece when the fastener driving element has reached the end of its drive stroke. A relationship of this type has, in the past, actually aided in the bump firing operation in that it has the effect of tending to move the entire device against the manual pressure of the operator away from the workpiece, thus insuring that the trigger valve will be moved to its inoperative position to commence the return stroke immediately after the drive stroke. However, where the pneumatic system of the device is modified to automatically recycle, the movement of the actuating valve into its inoperative position has the effect of stopping the automatic recycle. Consequently, under auto-fire actuation the provision of a work contacting member which may allow the actuating valve to move into its inoperative position as a result of recoil of the device following the completion of the drive stroke can have the effect of disrupting the automatic cycle of the device.

Accordingly, it is an object of the present invention to provide a fastener driving device of the type described capable of being operated in single fire, bump fire, drag fire and auto-fire fashion and which prevents disruption of the auto-fire cycle due to recoil while at the same time maintaining an overextended length of the fastener driving element sufficient to insure full penetration of the fasteners into the workpiece.

This result is achieved in accordance with the principles of the present invention by providing a motion transmitting mechanism between the work contacting member and trigger valve which includes a motion transmitting member and a spring means between the work transmitting member and the work contacting member. The work contacting member extends outwardly beyond the end of the fastener driving element when the latter is in its fastener driven position a predetermined distance and the spring means is arranged to transmit the inward movement of the work contacting member generally through the predetermined distance to the motion transmitting member, subsequent inward movement of the work contacting member resulting solely in the yielding movement of the spring without a corresponding movement to the motion transmitting member. The movement of the motion transmitting member is utilized, in conjunction with the movement of the trigger to effect movement of an interlock member which, in turn, serves to move the actuating valve into its operative position. In this way, when the fastener driving element moves through its drive stroke any tendency for the device to move away from the workpiece because of the extended length of the fastener driving element will simply result in a movement of the spring and work contacting member without an attendant movement of the motion transmitting member thus insuring that the trigger valve means will be maintained in its operative position for auto-fire operation by the pneumatic system.

A further objectof the present invention is the provision of a fluid pressure operated fastener driving device of the type described having an improved pneumatic system for effecting autofire.

Another object of the present invention is the provision of a fluid pressure operated fastener driving device of the type described having an improved mechanical interlock linkage for effecting movement of the actuating valve into its operative position in response (1) to the simultaneous actuation of the work contacting member and trigger, (2) to the actuating of the work contacting member when the trigger is actuated, or (3) to the actuation of the trigger when the work contacting member is actuated.

A further object of the present, invention is the provision of a fluid pressure operated fastener driving device of the type described which is simple in construction, efficient in operation and economical to manufacture and maintain.

These and other objects of the present invention will be come more apparent during the course of the following detailed description and appended claims. The invention may best be understood with reference to the accompanying drawings wherein an illustrative embodiment is shown.

In the drawings: I

FIG. 1 is a side elevational view of a fluid pressure operated fastener driving device embodying the principles of the present invention with certain parts shown in vertical section, the trigger and work contacting member being illustrated in their normal inoperative position;

FEG. 2 is a view similar to FIG. 1 showing the trigger and work contacting member in their operative position and the fastener driving means in its fastenerdrivcn position at the end of the work stroke;

FIG. 3 is a fragmentary side elevational view of the device illustrating the side thereof opposite to that shown in FIGS. 1

and 2;

FIG. 4 is a sectional view taken along the line 4-4 of FIG. 1; FIG. 5 is a sectional view taken along the line 5-5 of FIG. l; FIG. 6 is a fragmentary sectional view of the manually controlled actuating mechanism showing the position of the parts when the work contacting member is disposed in its operative position and the trigger member is disposed in its inoperative position; and

PEG. 7 is a fragmentary sectional view of the manually controlled actuating mechanism showing the position of the partswhen the work contacting member is disposed in its inoperative position and the trigger member is disposed in itsoperative position.

Referring now more particularly to the drawings, there is shown therein a fluid pressure operated fastener driving device, generally indicated at 10, embodying the principles of the present invention.

As a convenience, the device will be described in an orientation operable to drive fasteners downwardly into a horizontal workpiece, although it will be understood that the device is not limited to such application but can be used to drive fasteners into vertical workpieces or beneath horizontal workpieces, as well as workpieces of any other orientation. Consequently, it will be understood that terms such as vertical," horizontal," above," below," forwar "rearward," etc. as used herein are to be construed in their relative sense.

The device 10 includes a housing 12 to which is connected by suitable conventional means a magazine assembly, generally indicated at 14, having a nose piece assembly, generally indicated at 16, fixedly connected at its forward end to the magazine assembly and defining a vertically extending drive track into which successive fasteners are fed horizontally from the magazine assembly in accordance with conventional practice. It will be understood that the magazine assembly 14 may be of any known construction for feeding successive fasteners of any known construction as, for example, staples, T-head nails, pins, headed nails and the like.

Mounted for movement through the drive track 18 is an elongated fastener driving element 20 having a cross-sectional configuration compatible with the cross-sectional configuration of the drive track and the particular fastener which is fed thereto from the magazine assembly 14. The housing 12 contains a fluid pressure operated system, generally indicated at 22, for effecting movement of the fastener driving element between fastener receiving and fastener driven positions, through an operative cycle or cycles under the manual control of an operator by an actuating mechanism, generally indicated at 24.

The operating cycle of the fastener driving element 20 includes a vertically downward drive stroke from the fastener receiving position to the fastener driven position and a vertically upward return stroke from the fastener driven position to the fastener receiving position. During the drive stroke, a fastener, such as designated by the reference character F in FIGS. 1 and 2, which has been fed into the drive track 18 from the magazine assembly 14 prior to the commencement of the drive stroke is engaged by the lower end of the fastener driving element and moved downwardly through the drive track and outwardly therefrom into a workpiece such as the workpiece designated by the reference character W in FIG. 2. Thus, during each operating cycle of the fastener driving element 20 a fastener F is fed to the drive track and driven outwardly thereof by the fastener driving element into the workpiece W.

The fluid pressure operated system 22 includes a fluid pressure reservoir 26 defined by a generally horizontally extending hollow handle portion 28 forming an integral part of a main casting of the housing 12. In accordance with'conventional practice, the rearward end of the reservoir is provided with a fitting (not shown) adapted to be connected with one end of a pressure line, the opposite end of which is connected with a suitable source of fluid under pressure as, for example, a compressor or the like (also not shown).

The main casting of the housing 12 also includes a generally vertically extending forward portion 30 within which a vertically extending cylinder 32 is mounted. The cylinder 32 defines a vertically extending cylindrical drive chamber 34 within which a drive piston assembly 36 is slidably mounted. As best shown in FIGS. 1 and 2, the drive piston assembly 36 is in the form of a generally inverted cup-shaped piston member 38, having an annular flange 40 extending radially outwardly from the lower end thereof. The periphery of the annular flange is suitably grooved to receive an O-ring seal 42 which slidably sealingly engages the interior periphery of the cylinder 32. The interior central portion of the piston member 38 has a downwardly facing annular recess formed therein for receiving a disc-shaped pad 44, the central lower portion of which is adapted to engage the upper end of the fastener driving element 20. At a position spaced below the upper end of the fastener driving element 20, the latter is apertured to receive therethrough a pin 46 which, in turn, seats within an upwardly facing recess 48 formed in a generally cylindrical pad 50. The upper periphery of the pad includes a radially extending flange portion 52 which is adapted to engage within a correspondingly shaped annular recess 54 fonned in the interior periphery of the piston member 38.

The upper end of the drive chamber 34 is arranged to be alternately communicated with the fluid under pressure within the reservoir 26and with the atmosphere by the action of a main control valve, generally indicated at 56. To this end, the main casting of the housing 12 has a vertical bore 58 extending downwardly into communication with the reservoir 26 in parallel relation to the cylinder 32. A counterbore 60 is formed in the upper end of the bore 58 and an annular valve insert 62 is engaged within both the bore 58 and counterbore 60. The exterior periphery of the insert is sealed with respect to the bore and counterbore by any suitable means, such as an O-ring 64, as shown in FIGS. 1 and 2. The valve insert 62 provides a lower relatively large inlet opening 66, the lower end of which communicates with the reservoir 26 and provides an annular valve seat 68 surrounding the inlet opening.

The upper end of the inlet opening 66 communicates with the central interior of the valve insert 62 which has a lateral passage 70 extending horizontally therefrom which communicates with the upper end of the drive chamber 34 through a correspondingly shaped lateral passage 72 formed in the main casting of the housing 12. The upper end of the valve insert 62 is formed with a relatively small exhaust or outlet opening 74 concentric with the inlet opening 66 which communicates at its lower end with the central interior of the valve insert 62.

The main control valve 56 includes a main valve member 76 having an annular flange 78 extending radially outwardly therefrom for receiving an annular inlet valve element 80. The valve element 80 is retained in engagement with the flange 78 by a frustoconical portion 82 having a valve stem portion 84 extending upwardly therefrom. Formed on the upper end of the valve stem portion 84 is an enlarged portion of a size to engage within the exhaust opening 84 having its exterior periphery formed with an annular groove to receive an annular exhaust valve element 86 in the form of an O-ring or the like.

The main control valve member 76 is mounted within the housing 12 for vertical reciprocatory movement between two limiting positions. As shown in FIG. 1 in its upper limiting position, the inlet valve element 80 engages the valve seat 68 closing off communication of the fluid under pressure within the reservoir 26 from the drive chamber 34, the exhaust valve element 86 extending above the exhaust outlet 74 thus communicating the driving chamber with the atmosphere in a manner hereinafter more fully described. As shown in FIG. 2, when the main valve member 76 is in its lower limiting position, the inlet valve element 80 is disposed away from the valve seat 68 thus communicating the fluid under pressure within the reservoir 26 with the drive chamber 34, the exhaust valve element 86 being in sealing relation with the exhaust outlet 74.

The main valve member 76 is moved between those limiting positions by a pilot piston 88 formed integrally on the lower end of the valve member 76 and mounted within a cylindrical pilot pressure chamber 90 formed in the adjacent portion of the main casting of the housing 12. The pilot pressure within the pilot chamber 90 is controlled by a manually actuated or trigger valve member 92 which is normally biased, as by a coil spring 94 into a position preventing the exhaust of pilot pressure from the chamber. Pilot pressure for the pilot chamber 90 is obtained directly from the reservoir 26 as by a restricted orifice 96 extending through the periphery of the valve member 76.

Since the pilot piston 88 is of a diameter greater than the effective diameter of the valve element 80 (the greatest diameter dimension which contacts valve seat 68) and reservoir pressure acts in opposite directions upon both of these diameters at all times, pilot pressure acting on the piston 88 normally will effect movement of the main valve into its uppermost limiting position, closing off communication of the reservoir with the drive chamber.

The trigger valve member 92 forms a part of the manually controlled actuating mechanism 24 and is adapted to be moved from its normal position closing off the exhaust of the pilot pressure within the pilot chamber to an operative position communicating the pilot chamber with the atmosphere by the operation of the manually controlled actuating mechanism 24 in a manner to be hereinafter more fully described.

As best shown in FIGS. 1 and 2, the actuating valve 92 is preferably in the form of a cylindrical actuating member disposed within a bore 98 formed in the main casting of the housing 12 concentric with the main control valve 56. An 0- ring seal 100 is mounted in ariappropriate annular groove formed in the exterior peripheryof the cylindrical valve member for sealing engagement with the bore 98. Formed in the upper end of the bore 98 is a counterbore 102 surrounding the upper end of which is an upwardly facing valve seat 104. The actuating valve 92 includes an exhaust valve element 106 which is preferably in the form of an annular seal of a size to engage the valve seat 104.

The counterbore 102 forms a part of an exhaust passageway for the pilot chamber 90 which is controlled by'an auto-fire valve, generally indicated at 108, for alternatively opening and closing the exhaust passageway to alternatively pressurize and exhaust the pilot pressure to effect repeated movements of the main control valve 56 between its limiting positions so long as the actuating valve 92 is disposed in its operative position. To this end, the exhaust passageway includes a lateral bore 110, which communicates at one end with the lower end of the counterbore 102 and at its other end with a vertical bore 112 formed in the main casting of the housing 12. The upper end of the bore 112 communicates with a registering opening formed in a lower gasket 114 which is preferably of resilient material such as rubber, plastic or the like. As best shown in FIGS. 1 and 2, the gasket 114 is mounted on the upper end of the main casting of the housing 12, throughout the periphery thereof, and in engagement with a shoulder 116 formed on the upper, outer periphery of the valve insert 62.

Mounted above the lower gasket 114, in abutting relation thereto, is a plate 118 having anopening, similar to the opening in the gasket 114 which registers with the upper end of the vertical bore 112. Mounted in abutting relation to the upper surface of the plate 118 is an upper gasket 120, the entire sandwich including the upper and lower gaskets 114 and 120 and the intermediate plate 118 being detachably secured to the main casting by a cap member 122, as by a plurality of bolts 124 or the like, extending through all of the structure and threadedly engaged within the main casting of the housing 12.

The auto-fire valve 108 is carried within the cap member 122 and includes a downwardly facing counterbored recess defining a chamber 126 disposed inwardly of the counterbore of the recess. A circular diaphragm 128 is disposed within the counterbored portion of the recess and is retained therein by an annular exhaust valve member 130. The valve member 130 is formed with a central opening 140 which forms a part of the pilot pressure chamber exhaust passageway having its lower end communicated with the vertical bore 112, as by an elonit can be seen that when chamber 126 is pressurized, diaphragm 128 will move into pressure engagement with the valve seat 144 closing the pilot pressure exhaust passageway. When the chamber 126 is exhausted to atmosphere, pilot pressure within the exhaust passageway including the central opening will move the diaphragm 128 upwardly, thus communicating the pilot pressure with the annular space between the valve member 130 and the diaphragm 128. This space is communicated with the atmosphere through a port 146 formed in the valve member 130 adjacent its periphery. The upper gasket 120 includes an opening 148 which communicates with the port 146 and with one end of an elongated slot 150 formed in the plate 118 therebelow. The opposite end of the slot 150 communicates with a radial extension of an annularopening 152 formed in the upper gasket 120 concentric with the valve insert 62. Preferably, the cap member 122 is apertured, as indicated at 154, concentric with the valve insert 62 and an exhaust cap assembly 156 is mounted within the aperture 154 to deflect the air under pressure exhausting to the atmosphere laterally away from the hand of the operator through a discharge opening 157. The exhaust cap assembly 156 also serves to protect the exhaust valve element 86 of the main control valve 56 from damage.

As shown in FIGS. 1 and 2, the fluid pressure operated system 22 includes a conventional plenum chamber system for effecting the return stroke of the fastener driving element 20. To this end, the drive portion 30 of the housing 12 is formed with a plenum chamber 158 in surrounding relation to the exterior periphery of the cylinder 32. The upper end of the plenum chamber is sealed with respect to the cylinder by any suitable means, such as an O-ring seal 160 mounted within an appropriate annular groove in the upper interior periphery of the main casting of the housing 12 and disposed in engagement with the exterior periphery of the cylinder 32.

- As best shown in FIG. 4, the opposite lateral sides of the lower end of the cylinder 32 are communicated directly with the lower end of the plenum chamber 158. ln this regard, it should be noted that the main casting has a counterbored opening formed in the lower end portion thereof, concentric with the cylinder 32 within which is engaged the lower end of a bumper pad 172. The bumper pad 172 is formed with a central opening 174 of a size somewhat greater than the size of the fastener driving element 20 so as to provide part of an exhaust passageway for the bottom of the cylinder when the fastener driving element 20 is disposed in its uppermost fastener receiving position. Preferably, a plate 176 is secured to the main casting below the bumper pad 172, the latter being detachably secured to the main casting by a series of bolts 178 or the like which also extend through the adjacent portion of the magazine assembly to detachably secure the forward end of the latter to the main casting of the housing 1 2. As best shown in FIGS. 1 and 2, the plate 176 has a restricted passage 179 therein which forms the remaining part of the exhaust passageway provided by the opening 174.

In accordance with conventional practice, the cylinder 32 is formed with an opening 180 which is disposed in a position slightly above the O-ring 42 of the piston assembly 36 when the latter is disposed in its lowermost fastener driven position, as best shown in FIG. 2. It will be understood that the plenum return system operates in conventional fashion. Thus, during the drive stroke of the drive piston assembly 36, the air within the cylinder below the piston is initially, at least partially, discharged through the exhaust passageway provided by the opening 174 and passage 179. I

During the latter portion of the drive stroke, the air within the cylinder 32 below the piston assembly 36 may be somewhat compressed into the plenum chamber 158. When the piston assembly reaches the end of its drive stroke, the engagement of the piston pad with the pad 172 seals off any exhaust through the aforesaid exhaust passageway while at the same time the air under pressure acting on the upper surface of the piston enters opening 180 to immediately pressurize the plenum chamber 158 to substantially full reservoir pressure.

The charging of the plenum chamber 158 with fluid under pressure in the manner indicated above, is used as a pressure signal to operate the auto-fire valve 108. To this end, the diaphragm chamber 126 thereof is communicated with the plenum chamber 158 through a series of passages including a vertical port 182, communicating with the central portion of the chamber 126, a transverse port 184 communicating at one end with the port 182 and at its other end with a vertical bore 186, the port 182 and bores 184 and 186 being formed in the cap member 122. The lower end of the bore 186 communicates with the upper end of a vertical bore 188 formed in the main casting through a series of registering openings 190 formed in the upper gasket 120, plate 118 and lower gasket 114. The lower end of the bore 188 communicates with the upper end of the plenum chamber 158.

Preferably, the bore 184 is counterbored as indicated at 192 to threadedly receive an adjusting member 194 having a frustoconical inner end portion 196 which is adapted to be positioned within the adjacent end of the bore 184 to provide an adjustable restriction to the flow of fluid from the plenum chamber 158 to the diaphragm chamber 126 and vice versa.

Referring now more particularly to FIGS. 3 and 4, the manually controlled actuating mechanism 24 preferably includes a trigger member 198 which, as shown, is of generally U-shaped construction, having a pair of forwardly extending tabs 200 which are apertured to receive a pivot pin 202 extending through the upper end portion of a pair of transversely spaced vertically extending ribs 204 forming an integral part of the main casting of the housing 12. The trigger member 198 is biased by its own weight into a normally inoperative limiting position wherein the bight portion of the trigger engages the adjacent outer surface of the ribs 204, as indicated at 206 in FIG. 1. The trigger member 198 is adapted to be engaged by the finger of an operator whose hand is in engagement with handle portion 28 and is mounted for pivotal movement about the pivot pin 202 in a counterclockwise direction as viewed in FlG. 1 into an operative position wherein the bight portion of the trigger engages a depending abutment 208 formed integrally on the main casting of the housing 12 as best shown in FIG. 2.

The manually controlled actuating mechanism 24 also preferably includes a work contacting member or contact trip element 210 which, as shown, is generally of L-shaped configuration including an annular horizontally extending portion and having a lower work engaging horizontal surface 212 and a vertical portion 214 extending upwardly therefrom.

The vertical portion 214 of the work contacting member 210 is mounted for vertical reciprocating movement with respect to the nose piece 16 between a lower nonnally inoperable limiting position and an upper operative limiting position. To this end, it will be noted that the nose piece includes a pair of cooperating vertically extending plates 216 and 218, the plate 216 having a transverse opening 220 formed therein through which the fasteners F from the magazine assembly 14 are fed to the drive track 18, the latter being defined by a slot formed in the plate 218 and the encompassed surfaces of the plate 216. The lower ends of the plates 216 and 218 define horizontal surface means 222 adapted to engage the surface of the workpiece W when the device is disposed in operative engagement therewith, as shown in FIG.

The vertical portion 214 of the work contacting member 210 has one surface thereof disposed in sliding engagement with the lower central exterior surface of the plate 218. The vertical portion 214 of the work contacting member 210 is guided for vertical sliding movement along the peripheral outer surface of the plate 218 by the lower end portion of a housing plate 224, the housing plate 224 together with the plates 216 and 218 being detachably secured to the magazine assembly 14 as by a pair of bolts 226.

The upper end of the vertical portion 214 has a tab 228 struck therefrom and bent downwardly and outwardly. The tab 228 is apertured to receive one end of a guide pin 230.

Mounted in surrounding relation to the guide pin 230, is a compression coil spring 232 which is adapted to transmit the vertical movement of the work contacting member 210 to a motion transmitting member, generally indicated at 234. The motion transmitting member 234 includes a front vertically extending portion 236 mounted in alignment with a vertical portion 214 of the work contacting member 210 in vertically spaced relation thereto. The upper end of the front vertical portion 236 has a tab 238 struck therefrom and bent downwardly and outwardly to engage the upper end of the coil spring 232 the lower end of which engages the tab 228. The tab 228 is apertured to receive the'uppe'r end of the guide pin 230.

The motion transmitting member 234 also includes an elongated bent section including a front portion 240 which extends laterally outwardly from the one side of the vertical portion 236 adjacent the lower end thereof, through an opening 242 in the housing plate 224, a rearwardly extending horizontal portion 244 and upwardly bent vertical portion 246 and a horizontally extending portion 248. Fixedly secured to the upper surface of the horizontal portion 248, as by welding or the like, is a guide rod 250 having a coil spring 252 disposed in surrounding relation thereto. The upper end of the guide rod 250 extends through an opening in a plate 254 mounted between the ribs 204, the upper end of the spring 252 engaging the plate 254 and the lower end-of the spring engaging the portion 248 so as to resiliently urge the motion transmitting member 234 downwardly into a lower limiting position wherein the lower surface of the horizontal portion 240 engages the adjacent surface of the opening 242 formed in the housing plate 224.

The upper end of the guide rod 250 includes a cam surface 256, which, when the member 234 is disposed in its normally biased limiting position, is disposed in spaced relation below one end of an interlock lever member 258. As best shown in FIGS. 1 and 2 the interlock member 258 is generally of U- shaped cross-sectional configuration having the central portion of its legs pivotally connected with the lower end of the actuating member 92, as by a pivot pin 260. The opposite end of the interlock member 258 has a depressed portion 262 formed in the bight portion thereof which is adapted to engage the adjacent surface of the trigger member 198.

OPERATION It will be noted that when the device 10 is in an inoperative condition as shown in FIG. 1, spring 94 acts to resiliently bias the main valve 56 into its closed upper limiting position. The spring 94 also serves to bias the actuating valve 92 into its closed position. Trigger member 198 is biased by its own weight into its inoperative position and spring 252 serves to bias the motion transmitting member 234 into its lowermost limiting position, spring 232 serving to likewise maintain the work contacting member 210 in its lowermost limiting position.

When the device 10 is connected with a source of fluid under pressure, reservoir 26 is immediately charged and this fluid pressure is free to pass into the pilot chamber through the restricted orifice 96. Thus, the pressure within the pilot chamber 90 serves to maintain the main control valve 56 in its closed position wherein the upper end'of the drive chamber 34 is communicated with the atmosphere through the open exhaust valve element 86. It will also be understood that the drive piston assembly 36 will normally be disposed in its uppermost limiting position all as shown in FIG. 1.

The fluid pressure operated system 22 is actuated by moving the actuating valve 92 from its normal inoperative closed position into its operative open position. This actuation requires a manual movement of the trigger member 198 and of the work contacting member 210 into their operative positions. The operation of the interlock lever 258 is such that the actuating valve will be moved into its operative position in response to any one of the three following conditions: (1) a tions; (2) a movement of the work contacting member 210 into its operative position when the trigger member 198 is disposed in its operative, position; and (3) a movement of the trigger member 198 into its operative position when the work contacting member 210 is disposed in its operative position.

With reference to FIG. 6, it will be noted that a movement of the work contacting member 210 into its operative position, while the trigger member 198 is in its inoperative position, will merely result in moving the cam surface 256 into engagement with or into slightly spaced relation to the associated end of the interlock member 258. Under these circumstances, a pivotal movement of the trigger member 198 into its operative position will effect a counterclockwise pivotal movement of the interlock member about the cam surface 256 as a fulcrum, which movement will effect movement of the trigger valve into its operative position, as shown in FIG. 2. Likewise, with reference to FIG. 7, it will be noted that a movement of the trigger member 198, while the work contacting member 210 is d'mposed in its inoperative positionwill result in a counterclockwise pivotal movement of the interlock member 258 about the pivot pin 260 without any corresponding movement of the actuating valve 92. This pivotal movement of the interlock member 258 merely serves to move the end thereof which is normally spaced from the cam surface 256 when the work contacting member 210 is disposed in its normal inoperative position into engagement with or into slightly spaced relation to the cam surface 256. Under these conditions, movement of the work contacting member 210 into its operative position will effect a pivotal movement of the interlock member 258 about the projection 262 as a fulcrum, which movement will effect the movement of the trigger valve into its operative position as shown in FIG. 2.

The movement of the actuating valve 92 into its operative position opens the pilot exhaust passageway. Pilot pressure enters the counterbore 102, transverse bore 110, vertical bore 112, slot 142 and auto-fire valve opening 140. Since the diaphragm chamber 126 is receiving an atmospheric pressure signal from the plenum chamber 158, the pilot pressure in opening 140 moves the diaphragm 128 upwardly permitting the pilot pressure to exhaust to atmosphere through port 146, opening 148, slot 150, opening 152 and laterally outwardly of the exhaust cap assembly 156 through opening 157.

It will be noted that the-exhaust passageway provides a cross-sectional area which is greater than the cross-sectional area of the restricted orifice 96 and, consequently, the pilot pressure within the pilot chamber 90 will exhaust substantially to atmospheric conditions notwithstanding its continuous communication with the reservoir 26 through the restricted orifice 96. As soon as the pilot pressure drops pressure within the reservoir 26acting onthe upper surface of the pilot piston 68 will move the main valve 76 downwardly into its lowermost position wherein the inlet valve element 80 communicates the inlet 66 with the reservoir and exhaust valve element 86 closes the outlet 74. Reservoir pressure is then communicated to the upper end of the drive chamber 34 through openings 70 and 72 to effect the drive stroke of the piston assembly 36 and fastener driving element 20 connected thereto.

As previously noted, when the drive stroke is completed and the drive piston assembly 36 reaches its fastener driven position, plenum chamber 158 is charged with reservoir pressure from the drive chamber 34 through the opening 180. This pressure is communicated as a signal past the metering element 196 to the auto-fire valve diaphragm chamber 126. This pressure signal which acts on the entire surface of the diaphragm urges the central portion thereof into pressuretight engagement with the annular valve surface 144, thus closing the opening 140 of the pilot exhaust passageway. The reservoir pressure entering the pilot chamber 90 through the restricted orifice 96 cannow build up in the pilot chamber until it reaches a value sufficient to effect the upward movement of the main valve 76 into its closed position as shown in FIG. 1.

When the main control valve is in this position, the inlet valve element is disposed in engagement with the valve seat 68 closing off communication between the reservoir and the drive chamber 34 while the outlet opening 74 is communicated past the open exhaust valve element 86 to the atmosphere through the cap assembly 156 through opening 157. The exhaust of the fluid pressure above the drive piston 36 permits the fluid pressure charge within plenum chamber 158 to effect the rapid return stroke of the piston and fastener driving element 20 connected thereto into its uppermost position. During the latter portion of this movement the pressure within the plenum chamber 158 is allowed to restrictively exhaust to atmosphere through opening 174 and passage 179. The arrangement of the exhaust passageway provided by the opening 174 and passage 179 provides a constant restriction to exhaust except when the pad 50 is actually in engagement with the bumper pad 172. It will be understood that a variable restriction may be provided in accordance with conventional practice, wherein a lesser restriction taken place when the piston is adjacent its uppermost position.

The exhaust of the plenum chamber 158 serves as a pressure signal to condition theauto-fire valve 108 to unblock the pilot chamber exhaust passageway and thereby commence the drive stroke of the next cycle. In this regard, it will be noted that as soon as the pressure within the auto-fire valve diaphragm chamber 126 reduces to a value sufficient to permit the pressure in the. opening 140 to move the diaphragm out of engagement with the seat 144, the pilot chamber will begin to exhaust which, when it reaches a predetermined lower pressure condition, will permit the main valve 76 to be moved downwardly into its open position to commence the drive stroke of the next cycle. Since the change in pressure within the auto-fire valve diaphragm chamber 126 serves .to initiate the operations which effect automatic recycling and since the rate of change of the pressure within the chamber 126 can be controlled by adjusting the setting of member 194, the latter serves as a means for controlling the rate of the cycle of operation. By adjusting the member 194 to provide a greater restriction to air flow thereby, the speed with which a cycle of operation is completed is reduced. Conversely, by adjusting the member 194 so as to provide less restriction to air flow thereby, the speed with which a cycle of operation is completed is increased.

It will be understood that the device will continue to recycle automatically so long as the actuating valve 92 is maintained in its operating position by the actuating mechanism 24. In normal auto-fire operation, the operator moves the device along the surface of a workpiece W while continuously depressing the trigger member 198 and maintaining the surface 222 of the nose piece 16 in engagement with the surface of the workpiece W.

In accordance with conventional practice, it is sometimes desirable to provide the fastener driving element with a length such that when it is disposed in its fastener driven position, the lower fastener engaging surface thereof extends outwardly beyond the surface 222 of the nose piece 16 a predetermined distance, as, for example, the distance designated by the reference character X in FIG. 2. The work contacting surface 212 of the work contacting member 210 when the latter is disposed in its normally biased inoperative position, is disposed outwardly of the nose piece surface 222, a distance which is generally equal to the distance X plus the distance designated by the letter Y equal to the movement of the motion transmitting member 234 necessary to effect the movement of the trigger valve'92 into its operative limiting position. It will be noted, however, that since the movement of the work contacting member 210 is transmitted to the motion trans mitting member 234 by the spring 232, the total movement of the motion transmitting member 234 can be less than that of the work contacting member 210. Preferably, the total movement of the motion transmitting member is generally equal to the distance Y and it will be noted that the upper surface of the vertical portion 236 thereof will engage the adjacent lower surface of the plate 176 when the motion transmitting member 240 has moved with the work contacting member through the distance Y. Subsequent movement of the work contacting member through the distance X will result in a yielding move ment of the spring 232 without a corresponding movement of the member 234.

With this arrangement, it will be noted that in the event that the movement of the fastener driving element into its fastener driving position should result in a recoil movement of the entire device away from the work contacting surface in a range which is generally equal to the distance X, the work contacting member 210 alone will move under the action of spring 232 relative to the housing with substantially no movement of member 234 thereby preventing any undesired closing movement of the actuating valve 92 which would have the effect of disrupting the automatic cycling of the fluid pressure operating system 22.

It will be understood the operation of the spring 232 would have the same advantages in a device, without fastener driving element overtravel, which had sufficient recoil to cause the device to move off of the workpiece; Moreover, such operation would have advantages where the contact trip constitutes the only manual means for actuating the device.

It will be understood that the time required to automatically cycle the device is dependent upon the setting of the frustoconical needle valve 196 within the bore 184. Moreover, by adjusting the threaded member so as to provide the slowest speed of automatic cycle, the operator is enabled to effect manual operation either in single fire, bump fire or drag fire fashion before automatic recycling will take place.

It thus will be seen that the objects of this invention have been fully and effectively accomplished. It will be realized, however, that the foregoing specific embodiment has been shown and described only for the purpose of illustrating the principles of this invention and is subject to extensive change without departure from such principles. Therefore, this invention includes all modifications encompassed within the spirit and scope of the following claims.

We claim:

1. A fastener driving device comprising:

a housing having means defining a pressure reservoir for receiving and containing fluid under pressure supplied thereto from a source of fluid under pressure;

means defining a drive track for receiving successive fasteners to be driven from a supply of such fasteners fed thereto;

fastener driving means carried by said housing for movement from a fastener receiving position through said drive track in a drive stroke into a fastener driven position and from said fastener driven position through a return stroke into said fastener receiving position;

means within said housing defining a driving pressure chamber disposed in fluid communicating relation to said fastener driving means;

main control valve means movable between a first position communicating said driving chamber with the atmosphere and closing communication between said driving chamber and said reservoir and a second position communicating said driving chamber with said reservoir and closing off communication of said driving chamber with the atmosphere so that said fastener driving means will be moved through said drive stroke in response to the movement of said main valve means into said second position and through said return stroke in response to the movement of said main valve means into said first position;

means defining a pilot pressure chamber;

a pilot pressure actuated member disposed in pressure communicating relation with said pilot chamber for movement from a first position into a first position in response to the communication of pilot pressure within said pilot chamber and from said second position into said first position in response to the exhaust of said pilot chamber to atmosphere;

means operable in response to the movement of said pilot pressure actuated member into said first position for effecting movement of said main valve means into said second position and operable in response to the movement of said pilot pressure actuated member into said second position for effecting movement of said main valve means into said first position;

means defining a restricted orifice continuously communicating said reservoir with said pilot chamber;

means defining an exhaust outlet for said pilot chamber of a size greater than said restricted orifice;

manually operable valve means mounted for movement between a normally closed position preventing communication of said pilot pressure chamber with said exhaust outlet and a manually actuated opened position communicating said pilot chamber with said exhaust outlet;

auto-fire valve means arranged in series with said manually operable valve means between said pilot chamber and said exhaust outlet for controlling communication of said pilot chamber and said exhaust outlet when said manually operable valve means is disposed in said manually actuated opened position;

said auto-fire valve means including a valve member mounted for movement between an opened position communicating said pilot pressure chamber with said exhaust outlet when said manually operated valve means is disposed in said manually actuated opened position and a closed position preventing communication of said pilot chamber with said exhaust outlet when said manually operated valve means is disposed in said manually actuated opened position;

first pressure surface means operatively associated with said valve member and disposed in pressure communicating relation with said pilot chamber operable to bias said valve member into said opened position in response to the communication of pressure in said pilot chamber therewith;

second pressure surface means operatively associated with said valve member of an effective area sufficiently greater than the effective area of said first pressure surface means to bias said valve member into said closed position in response to the communication of signal pressure therewith with a force greater than the force acting on said first pressure surface means biasing said valve member into said opened position; and

means for communicating with said second pressure surface means a signal pressure, separate from said pilot pressure, established as a result of the movement of said pilot pressure actuated member into said second position, which signal pressure is dissipated as a result of the movement of said pilot pressure actuated member into said first position so that when said manually operable valve means is disposed in said manually actuated opened position said autofire valve means is operable to effect movement of said fastener driving means through continuous drive stroke and return stroke cycles until said manually operable valve means is moved into said closed position.

2; A fastener driving device as defined in claim 1 including:

means defining a return plenum chamber;

means for charging said return plenum chamber with fluid under pressure when said fastener driving means has moved through its drive stroke;

means for communicating the fluid pressure charge of said plenum chamber with said fastener driving means to effect the return stroke thereof in response to the movement of said main valve means into its first position;

means for exhausting the fluid pressure charge of said plenum chamber when said fastener driving means has completed its return stroke; and

wherein said signal pressure communicating means include means defining a passageway communicating said plenum chamber with said second pressure surface means so that the fluid pressure charge of said plenum chamber constitutes said signal pressure.

3. A fastener driving device as defined in claim'2 including a flow restricting member adjustably mounted within said passageway for determining the rate at which said signal pressure is communicated with and dissipated from said second pressure surface means to thereby determine the rate of the continuous drive stroke and return stroke cycles.

4. A fastener driving device asdefined in claim 3 wherein said valve member comprises a flexible annular diaphragm mounted with its periphery in confined relation, one surface of said diaphragm defined by the peripheral confinement thereof constituting said second pressure surface means, a central portion of the opposite surface of said diaphragm being engageable with an annular valve seat and constituting said first pressure surface means.

5. A fastener driving device as defined in claim 1 wherein said driving chamber defining means comprises a cylinder, said housing including a main casting having a bore extending downwardly from the upper end portion thereof receiving said cylinder, and a cap assembly fixedly secured to said main casting above said cylinder, said auto-fire valve means being carried by said cap assembly.

6. A fastener driving device as defined in claim 5 wherein said means for effecting movement of said main valve means in response to the movement of said pilot pressure actuated member comprises an elongated member mounted within said housing with its longitudinal axis parallel with the axis of said cylinder, said elongated member having a piston portion formed integrally on the lower end thereof which constitutes said pilot pressure actuated member, the lower surface of said piston portion being in communication with said pilot chamber and the upper surface thereof being in communication with said reservoir, said main valve means including an annular inlet valve element of an effective diameter less than said piston portion carried by said elongated member in upwardly spaced concentric relation to said piston portion and having an upwardly facing annular surface for engaging an annular valve seat fixed with respect to said housing in a position between said reservoir and the upper end of said cylinder and an annular exhaust valve element of a diameter less than said inlet valve element carried by said elongated member in upwardly spaced concentric relation to said inlet valve element for engaging an annular valve seat fixed with respect to said housing in a position between the upper end of said cylinder and a portion of said cap assembly having an exhaust opening therein.

7. A fastener driving device as defined in claim 1 wherein said housing includes a handle portio ntarranged to be gripped by the hand of an operator and a nose piece defining operatively fixed surface means engageable with a workpiece when said housing is manually moved by the operator into operative relation with a workpiece;

said fluid pressure operated fastener driving means includes a fastener driving element having a fastener engaging end spaced outwardly beyond said work engaging surface means when said fastener driving means is disposed in said fastener driven position;

a work contacting member carried by said housing for limited movement between a normal inoperative position and an operative position, said work contacting member including work engaging surface means disposed outwardly of said fixed surface means when said work contacting member is disposed in said inoperative position a predetermined distance beyond the position of said fastener driving element when the latter is disposed in said fastener driven position and in alignment with said fixed surface means when said work contacting member is in said operative position;

a motion transmitting member carried by said housing for limited movement between a normally inoperative position and an operative position;

spring means operatively connected between said members for transmitting the movement of said work contacting member from said inoperative position generally through said predetermined distance to said motion transmitting member to move the latter from said inoperative position to said operative position and for yielding during the remainder of the movement of said work contacting member into said operative position while said motion transmitting member remains immobile;

a trigger carried by said housing in a normal limited inoperative position operable to be engaged by a finger of the operator when said handle portion is manually gripped for manual movementinto a limited operative position; and

interlock means operatively connected between said trigger and said motion transmitting member for effecting movement of said manually operable valve means into the opened position thereof in response (l) to the simultaneous movement of said motion transmitting member and said trigger into their operative position, (2) to the movement of said motion transmitting member into its operative position when said trigger is in its operative position or (3) to the movement of said trigger into its operative position when said motion transmitting member is in its operative position, the yielding movement of said spring means preventing undesired movement of said manually operable valve means into said closed position by a relative movement of said work contacting member away from its operative position as a result of a movement of the housing away from the work piece against the manual pressure of the operator on the handle portion by the action of the fastener driving element moving into said fastener driven position.

8. A fastener driving device as defined in claim 7 wherein said manually operable valve means includes an actuating member having a depending end portion and wherein said interlock means includes an elongated interlock member, means pivotally interconnecting said interlock member intermediate its ends with the depending end portion of said actuating member, means connecting one end of said interlock member with said motion transmitting member for movement thereby in response to the movement of said work contacting member from said inoperative position to said operative position, and means for connecting the other end of said interlock member with said trigger for movement in response to the movement of said trigger from said inoperative position to said operative position.

9. A fastener driving device comprising a housing defining a handle portion arranged to be gripped by the hand of an operator and a nose piece defining operatively fixed surface means engageable with a workpiece when said housing is manually moved by the operator into operative relation with a workpiece;

fluid pressure operated fastener driving means including a fastener driving element carried by said housing for movement from a fastener receiving position through a drive stroke into a fastener driven position and from said fastener driven position through a return stroke into said fastener receiving position;

manually operable valve means normally disposed in an inoperative position movable into an operative position to actuate said fluid pressure operated means;

a work contacting member carried by said housing for a limited movement between a normal inoperative position and an operative position, said work contacting member including work engaging surface means disposed outwardly of said fixedsurface means when said work contacting member is disposed in said inoperative position a predetermined distance beyond the position of said fastener driving element when the latter is disposed in said fastener driven position and in alignment with said fixed surface means when said work contacting member is in said operative position;

a motion transmitting member carried by said housing for limited movement between a normally inoperative position and an operative position;

spring means operatively connected between said members for transmitting the movement of said work contacting member from said inoperative position generally through said predetermined distance to said motion transmitting member to move the latter from said inoperative position to said operative position and for yielding during the remainder of the movement of said work contacting member into said inoperative position while said motion transmitting member remains immobile;

a trigger carried by said housing in a normal limited inoperative position operable to be engaged by a finger of the operator when said handle portion is manually gripped for manual movement into a limited operative position; and

interlock means operatively connected between said trigger and said motion transmitting member for effecting movement of said valve means into the operative position thereof in response (1) to the simultaneous movement of said motion transmitting member and said trigger into their operative positions, (2) to the movement of said motion transmitting member into its operative position when said trigger is in its operative position or (3) to the movement of said trigger into its operative position when said motion transmitting member is in its operative position, the yielding movement of said spring means preventing undesired movement of said valve means into said inoperative position by a relative movement of said work contacting member away from its operative position as a result of a movement of the housing away from the work piece against the manual pressure of the operator on the handle portion.

10. A fastener driving device as defined in claim 9 wherein said work contacting member includes a vertically extending portion mounted adjacent said nose piece, said motion transmitting member includes a vertically extending portion disposed above said work contacting member portion and said spring means comprises a coil spring and means for mounting said coil spring between the vertically extending portions of said members.

11. A fastener driving device as defined in claim 10 wherein said coil spring mounting means includes a tab bent outwardly from each vertically extending portion engaging an end of said coil spring and a guide rod extending through said tabs and said coil spring.

12. A fastener driving device as defined in claim 11 including a housing plate secured to said nose piece generally enclosing said vertically extending portions, said tabs, said guide rod and said coil spring.

13. A fastener driving device as defined in claim 12 wherein said motion transmitting member further includes a second portion extending laterally outwardly through said housing place, a third portion extending horizontally rearwardly from said second portion, a fourth portion extending upwardly from said second portion, a fifth portion extending laterally from said fourth portion and a sixth portion extending upwardly from said fifth portion, a second coil spring disposed in surrounding relation to said sixth portion having its ends operatively engaged with said fifth portion and said housing respectively so as to bias said motion transmitting member into its inoperative position,

14. A fastener driving device as defined in claim 13 wherein said manually operable valve means includes an actuating member having a depending end portion and wherein said interlock means includes an elongated interlock member, means pivotally interconnecting said interlock member intermediate its ends with the depending end portion of said actuating member, a lost motion connection between one end of said interlock member and the upper end of the fifth portion of said motion transmitting member and a lost motion connection between the other end of said interlock member and said trigger.

15 In a fastener driving device of the type including a housing, fluid pressure operated fastener driving means carried by said housing for movement through a fastener driving stroke and a return stroke, valve means including a depending actuating member carried by said housing for movement from a normally inoperative position into an operative position for effecting the operation of said fluid pressure operated means through said fastener driving stroke, a work contacting member carried by said housing for movement from an inoperative position to an operative position in response to the movement of said apparatus into cooperating engagement with a work piece, a trigger member carried by said housing for manual movement from an inoperative position to an operative position, and interlock means for effecting movement of said valve means into the operative position thereof in response l) to the simultaneous movement of said work contacting and said trigger members into their operative positions, (2) to the movement of said work contacting member into its operative position when said trigger member is in its operative position or (3) to the movement of said trigger member into its operative position when said work contacting member is in its operative position, the improvement which comprises said interlock means including an elongated interlock member, means pivotally interconnecting said interlock member intermediate its ends with the depending end portion of said valve means actuating member, means connecting one end of said interlock member with said work contacting member for movement thereby inresponse to the movement of said work contacting member from said inoperative position to said operative position, and means for connecting the other end of said interlock member with said trigger member for movement in response to the movement of said trigger member from said inoperative position to said operative position.

16. A fastener driving device comprising a housing defining a handle portion arranged to be gripped by the hand of an operator and a nose piece defining'operatively fixed surface means engageable with a workpiece when said housing is manually moved by the operator into operative relation with a workpiece;

fluid pressure operated fastener driving means including a fastener driving element carried by said housing for movement from a fastener receiving position through a drive stroke into a fastener driven position and from said fastener driven position through a return stroke into said fastener receiving position;

manually operable valve means normally disposed in an inoperative position movable. into an operative position to actuate said fluid pressure operated means;

a work contacting member carried by said housing for limited movement between a normal inoperative position and an operative position, said work contacting member including work engaging surface means disposed outwardly of said fixed surface means when said work contacting member is disposed in said inoperative position a predetermined distance beyond the position of said fastener driving element when the latter is disposed in said fastener driven position and in alignment with said fixed surface means when said work contacting member is in said operative position;

a motion transmitting member carried by said housing for limited movement between a normally inoperative position and an operative position;

spring means operatively connected between said members for transmitting the movement of said work contacting member from said inoperative position generally through said predetermined distance to said motion transmitting member to move the latter from said inoperative position to said operative position and for yielding during the remainder of the movement of said work contacting member into said inoperative position while said motion transmitting member remains immobile; and

means operatively connected with said motion transmitting member for effecting movement of said valve means into the operative position thereof when said motion transmitting member is disposed in its operative position. 

1. A fastener driving device comprising: a housing having means defining a pressure reservoir for receiving and containing fluid under pressure supplied thereto from a source of fluid under pressure; means defining a drive track for receiving successive fasteners to be driven from a supply of such fasteners fed thereto; fastener driving means carried by said housing for movement from a fastener receiving position through said drive track in a drive stroke into a fastener driven position and from said fastener driven position through a return stroke into said fastener receiving position; means within said housing defining a driving pressure chamber disposed in fluid communicating relation to said fastener driving means; main control valve means movable between a first position communicating said driving chamber with the atmosphere and closing communication between said driving chamber and said reservoir and a second position communicating said driving chamber with said reservoir and closing off communication of said driving chamber with the atmosphere so that said fastener driving means will be moved through said drive stroke in response to the movement of said main valve means into said second position and through said return stroke in response to the movement of said main valve means into said first position; means defining a pilot pressure chamber; a pilot pressure actuated member disposed in pressure communicating relation with said pilot chamber for movement from a first position into a first position in response to the communication of pilot pressure within said pilot chamber and from said second position into said first position in response to the exhaust of said pilot chamber to atmosphere; means operable in response to the movement of said pilot pressure actuated member into said first position for effecting movement of said main valve means into said second position and operable in response to the movement of said pilot pressure actuated member into said second position for effecting movement of said main valve means into said first position; means defining a restricted orifice continuously communicating said reservoir with said pilot chamber; means defining an exhaust outlet for said pilot chamber of a size greater than said restricted orifice; manually operable valve means mounted for movement between a normally closed position preventing communication of said pilot pressure chamber with said exhaust outlet and a manually actuated opened position communicating said pilot chamber with said exhaust outlet; auto-fire valve means arranged in series with said manually operable valve means between said pilot chamber and said exhaust outlet for controlling communication of said pilot chamber and said exhaust outlet when said manually operable valve means is disposed in said manually actuated opened position; said auto-fire valve means including a valve member mounted for movement between an opened position communicating said pilot pressure chamber with said exhaust outlet when said manually operated valve means is disposed in said manually actuated opened position and a closed position preventing communication of said pilot chamber with said exhaust outlet when said manually operated valve means is disposed in said manually actuated opened position; first pressure surface means operatively associated with said valve member and disposed in pressure communicating relation with said pilot chamber operable to bias said valve member into said opened position in response to the communication of pressure in said pilot chamber therewith; second pressure surface means operatively associated with said valve member of an effective area sufficiently greater than the effective area of said first pressure surface means to bias said valve member into said closed position in response to the communication of signal pressure therewith with a force greater than the force acting on said first pressure surface means biasing said valve member into said opened position; and means for communicating with said second pressure surface means a signal pressure, separate from said pilot pressure, established as a result of the movement of said pilot pressure actuated member into said second position, which signal pressure is dissipated as a result of the movement of said pilot pressure actuated member into said first position so that when said manually operable valve means is disposed in said manually actuated opened position said autofire valve means is operable to effect movement of said fastener driving means through continuous drive stroke and return stroke cycles until said manually operable valve means is moved into said closed position.
 2. A fastener driving device as defined in claim 1 including: means defining a return plenum chamber; means for charging said return plenum chamber with fluid under pressure when said fastener driving means has moved through its drive stroke; means for communicating the fluid pressure charge of said plenum chamber with said fastener driving means to effect the return stroke thereof in response to the movement of said main valve means into its first position; means for exhausting the fluid pressure charge of said plenum chamber when said fastener driving means has completed its return stroke; and wherein said signal pressure communicating means include means defining a passageway communicating said plenum chamber with said second pressure surface means so that the fluid pressure charge of said plenum chamber constitutes said signal pressure.
 3. A fastener driving device as defined in claim 2 including a flow restricting member adjustably mounted within said passageway for determining the rate at which said signal pressure is communicated with and dissipated from said second pressure surface means to thereby determine the rate of the continuous drive stroke and return stroke cycles.
 4. A fastener driving device as defined in claim 3 wherein said valve member comprises a flexible annular diaphragm mounted with its periphery in confined relation, one surface of said diaphragm defined by the peripheral confinement thereof constituting said second pressure surface means, a central portion of the opposite surface of said diaphragm being engageable with an annular valve seat and constituting said first pressure surface means.
 5. A fastener driving device as defined in claim 1 wherein said driving chamber defining means comprises a cylinder, said housing including a main casting having a bore extending downwardly from the upper end portion thereof receiving said cylinder, and a cap assembly fixedly secured to said main casting above said cylinder, said auto-fire valve means being carried by said cap assembly.
 6. A fastener driving device as defined in claim 5 wherein said means for effecting movement of said main valve means in response to the movement of said pilot pressure actuated member comprises an elongated member mounted within said housing with its longitudinal axis parallel with the axis of said cylinder, said elongated member having a piston portion formed integrally on the lower end thereof which constitutes said pilot pressure actuated member, the lower surface of said piston portion being in communication with said pilot chamber and the upper surface thereof being in communication with said reservoir, said main valve means including an annular inlet valve element of an effective diameter less than said piston portion carried by said elongated member in upwardly spaced concentric relation to said piston portion and having an upwardly facing annular surface for engaging an annular valve seat fixed with respect to said housing in a position between said reservoir and the upper end of said cylinder and an annular exhaust valve element of a diameter less than said inlet valve element carried by said elongated member in upwardly spaced concentric relation to said inlet valve element for engaging an annular valve seat fixed with respect to said housing in a position between the upper end of said cylinder and a portion of said cap assembly having an exhaust opening therein.
 7. A fastener driving device as defined in claim 1 wherein said housing includes a handle portion arranged to be gripped by the hand of an operator and a nose piece defining operatively fixed surface means engageable with a workpiece when said housing is manually moved by the operator into operative relation with a workpiece; said fluid pressure operated fastener driving means includes a fastener driving element having a fastener engaging end spaced outwardly beyond said work engaging surface means when said fastener driving means is disposed in said fastener driven position; a work contacting member carried by said housing for limited movement between a normal inoperative position and an operative position, said work contacting member including work engaging surface means disposed outwardly of said fixed surface means when said work contacting member is disposed in said inoperative position a predetermined distance beyond the position of said fastener driving element when the latter is disposed in said fastener driven position and in alignment with said fixed surface means when said work contacting member is in said operative position; a motion transmitting member carried by said housing for limited movement between a normally inoperative position and an operative position; spring means operatively connected between said members for transmitting the movement of said work contacting member from said inoperative position generally through said predetermined distance to said motion transmittinG member to move the latter from said inoperative position to said operative position and for yielding during the remainder of the movement of said work contacting member into said operative position while said motion transmitting member remains immobile; a trigger carried by said housing in a normal limited inoperative position operable to be engaged by a finger of the operator when said handle portion is manually gripped for manual movement into a limited operative position; and interlock means operatively connected between said trigger and said motion transmitting member for effecting movement of said manually operable valve means into the opened position thereof in response (1) to the simultaneous movement of said motion transmitting member and said trigger into their operative position, (2) to the movement of said motion transmitting member into its operative position when said trigger is in its operative position or (3) to the movement of said trigger into its operative position when said motion transmitting member is in its operative position, the yielding movement of said spring means preventing undesired movement of said manually operable valve means into said closed position by a relative movement of said work contacting member away from its operative position as a result of a movement of the housing away from the work piece against the manual pressure of the operator on the handle portion by the action of the fastener driving element moving into said fastener driven position.
 8. A fastener driving device as defined in claim 7 wherein said manually operable valve means includes an actuating member having a depending end portion and wherein said interlock means includes an elongated interlock member, means pivotally interconnecting said interlock member intermediate its ends with the depending end portion of said actuating member, means connecting one end of said interlock member with said motion transmitting member for movement thereby in response to the movement of said work contacting member from said inoperative position to said operative position, and means for connecting the other end of said interlock member with said trigger for movement in response to the movement of said trigger from said inoperative position to said operative position.
 9. A fastener driving device comprising a housing defining a handle portion arranged to be gripped by the hand of an operator and a nose piece defining operatively fixed surface means engageable with a workpiece when said housing is manually moved by the operator into operative relation with a workpiece; fluid pressure operated fastener driving means including a fastener driving element carried by said housing for movement from a fastener receiving position through a drive stroke into a fastener driven position and from said fastener driven position through a return stroke into said fastener receiving position; manually operable valve means normally disposed in an inoperative position movable into an operative position to actuate said fluid pressure operated means; a work contacting member carried by said housing for a limited movement between a normal inoperative position and an operative position, said work contacting member including work engaging surface means disposed outwardly of said fixed surface means when said work contacting member is disposed in said inoperative position a predetermined distance beyond the position of said fastener driving element when the latter is disposed in said fastener driven position and in alignment with said fixed surface means when said work contacting member is in said operative position; a motion transmitting member carried by said housing for limited movement between a normally inoperative position and an operative position; spring means operatively connected between said members for transmitting the movement of said work contacting member from said inoperative position generally through said predetermined distance to said mOtion transmitting member to move the latter from said inoperative position to said operative position and for yielding during the remainder of the movement of said work contacting member into said inoperative position while said motion transmitting member remains immobile; a trigger carried by said housing in a normal limited inoperative position operable to be engaged by a finger of the operator when said handle portion is manually gripped for manual movement into a limited operative position; and interlock means operatively connected between said trigger and said motion transmitting member for effecting movement of said valve means into the operative position thereof in response (1) to the simultaneous movement of said motion transmitting member and said trigger into their operative positions, (2) to the movement of said motion transmitting member into its operative position when said trigger is in its operative position or (3) to the movement of said trigger into its operative position when said motion transmitting member is in its operative position, the yielding movement of said spring means preventing undesired movement of said valve means into said inoperative position by a relative movement of said work contacting member away from its operative position as a result of a movement of the housing away from the work piece against the manual pressure of the operator on the handle portion.
 10. A fastener driving device as defined in claim 9 wherein said work contacting member includes a vertically extending portion mounted adjacent said nose piece, said motion transmitting member includes a vertically extending portion disposed above said work contacting member portion and said spring means comprises a coil spring and means for mounting said coil spring between the vertically extending portions of said members.
 11. A fastener driving device as defined in claim 10 wherein said coil spring mounting means includes a tab bent outwardly from each vertically extending portion engaging an end of said coil spring and a guide rod extending through said tabs and said coil spring.
 12. A fastener driving device as defined in claim 11 including a housing plate secured to said nose piece generally enclosing said vertically extending portions, said tabs, said guide rod and said coil spring.
 13. A fastener driving device as defined in claim 12 wherein said motion transmitting member further includes a second portion extending laterally outwardly through said housing place, a third portion extending horizontally rearwardly from said second portion, a fourth portion extending upwardly from said second portion, a fifth portion extending laterally from said fourth portion and a sixth portion extending upwardly from said fifth portion, a second coil spring disposed in surrounding relation to said sixth portion having its ends operatively engaged with said fifth portion and said housing respectively so as to bias said motion transmitting member into its inoperative position.
 14. A fastener driving device as defined in claim 13 wherein said manually operable valve means includes an actuating member having a depending end portion and wherein said interlock means includes an elongated interlock member, means pivotally interconnecting said interlock member intermediate its ends with the depending end portion of said actuating member, a lost motion connection between one end of said interlock member and the upper end of the fifth portion of said motion transmitting member and a lost motion connection between the other end of said interlock member and said trigger.
 15. In a fastener driving device of the type including a housing, fluid pressure operated fastener driving means carried by said housing for movement through a fastener driving stroke and a return stroke, valve means including a depending actuating member carried by said housing for movement from a normally inoperative position into an operative position for effecting the operation of said fluId pressure operated means through said fastener driving stroke, a work contacting member carried by said housing for movement from an inoperative position to an operative position in response to the movement of said apparatus into cooperating engagement with a work piece, a trigger member carried by said housing for manual movement from an inoperative position to an operative position, and interlock means for effecting movement of said valve means into the operative position thereof in response (1) to the simultaneous movement of said work contacting and said trigger members into their operative positions, (2) to the movement of said work contacting member into its operative position when said trigger member is in its operative position or (3) to the movement of said trigger member into its operative position when said work contacting member is in its operative position, the improvement which comprises said interlock means including an elongated interlock member, means pivotally interconnecting said interlock member intermediate its ends with the depending end portion of said valve means actuating member, means connecting one end of said interlock member with said work contacting member for movement thereby in response to the movement of said work contacting member from said inoperative position to said operative position, and means for connecting the other end of said interlock member with said trigger member for movement in response to the movement of said trigger member from said inoperative position to said operative position.
 16. A fastener driving device comprising a housing defining a handle portion arranged to be gripped by the hand of an operator and a nose piece defining operatively fixed surface means engageable with a workpiece when said housing is manually moved by the operator into operative relation with a workpiece; fluid pressure operated fastener driving means including a fastener driving element carried by said housing for movement from a fastener receiving position through a drive stroke into a fastener driven position and from said fastener driven position through a return stroke into said fastener receiving position; manually operable valve means normally disposed in an inoperative position movable into an operative position to actuate said fluid pressure operated means; a work contacting member carried by said housing for limited movement between a normal inoperative position and an operative position, said work contacting member including work engaging surface means disposed outwardly of said fixed surface means when said work contacting member is disposed in said inoperative position a predetermined distance beyond the position of said fastener driving element when the latter is disposed in said fastener driven position and in alignment with said fixed surface means when said work contacting member is in said operative position; a motion transmitting member carried by said housing for limited movement between a normally inoperative position and an operative position; spring means operatively connected between said members for transmitting the movement of said work contacting member from said inoperative position generally through said predetermined distance to said motion transmitting member to move the latter from said inoperative position to said operative position and for yielding during the remainder of the movement of said work contacting member into said inoperative position while said motion transmitting member remains immobile; and means operatively connected with said motion transmitting member for effecting movement of said valve means into the operative position thereof when said motion transmitting member is disposed in its operative position. 